JPH0815589A - Coated optical fiber for air feeding and air feeding method of coated optical fiber - Google Patents

Abstract

PURPOSE:To provide a coated fiber for air feeding capable of feeding a relatively brittle a wire by air flow without stopping even in the bent part of a pipeline. CONSTITUTION:(A) is the section of the wire 1 which is formed by using two pieces of optical fibers 2 and applying a coating 4 thereon together with a tear cord 3. (B) is the section of the front end wire 5 which is formed by applying a coating 7 of a foamed polyethylene on a rod member 6 of nylon. The outside diameter of the wire 1 is 0.5mum and the outside diameter of the front end member 5 is 0.9mum. The outside diameter of the front end member is larger. The rigidity is higher with the front end member 5. The wire 1 is fed in a short period of time without stopping even at the bend of the pipeline when the wire 1 is mounted with the front end member 5 at 5cm and is fed into the pipeline by the air flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical fiber line which is laid by a gas flow in an air flow path, and a method of laying an optical fiber line in a gas line using an air flow. is there.

[0002]

2. Description of the Related Art When an optical fiber is laid by using an air flow, if the pipe has a small bend, for example, a bend having a diameter of 1 m or less, the optical fiber will be stiff due to the rigidity of the optical fiber. The distal end of the optical fiber may be pressed against the inner wall surface of the conduit and pressed against it, which may increase the resistance, which may prevent the optical fiber from being transmitted.

In the cable laying method described in Japanese Patent Application Laid-Open No. 3-290604, a wire rod having a rigidity lower than that of the cable is attached to the tip end portion of the cable to be fed, and the tip end of the wire rod is attached to the tip end portion by the force of the air flow acting on the tip wire rod. Bend it to reduce the frictional force on the inner wall surface of the pipe at the tip,
It is intended to improve the transmission performance.

On the other hand, generally used optical fibers have a mainstream of 250 μm UV resin coated optical fibers which can be mounted in a small diameter and can be mounted at a high density in order to increase the number of cores that can be accommodated in a cable. In addition, with the development of optical communication networks, optical fibers are being installed from the end to the end. At this time, the optical fiber used for the original cable,
The optical fiber used at the end preferably has the same diameter from the viewpoint of connectivity. On the other hand, since the number of cores may be small at the end of the communication network, a more fragile optical fiber bundle of one core to several cores is often used.

However, in the case where such a fragile optical fiber bundle is used as a wire rod to carry the air flow to the tube, a new problem that has not existed before has occurred.

The problem is that, when the wire is fed, the tip of the wire sticks to the inner wall of the tube, and the part following the sticking portion meanders in the tube. When this phenomenon occurs, the wire rod bends, breaks, or does not move at the meandering point, making it impossible to send the wire.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and one or several optical fiber element wires are assembled and integrated by a thin resin. An object of the present invention is to provide an air-carrying core wire capable of sending a fragile wire material by an airflow without stopping at a curved portion of a pipe line, and an airflow laying method.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to an air-carrying optical fiber, in which one or several optical fiber strands are assembled,
It is characterized in that a tip wire rod having an outer diameter equal to or larger than the outer diameter of the wire rod and a bending rigidity larger than that of the wire rod is attached to the tip end of a relatively fragile wire rod integrated with a thin resin. Another feature is that the tip wire has a length of 5 cm or more.

Further, the present invention is a method of assembling one or several optical fiber strands and sending a relatively fragile wire rod integrated with a thin resin to a pipe line by an air flow,
It is characterized in that a tip end wire rod having an outer diameter larger than that of the wire rod and a bending rigidity larger than that of the wire rod is attached to the tip of the optical unit and is sent to the conduit by an air flow.

[0010]

According to the results of repeated studies conducted by the inventors of the present invention, it is known that the force exerted on the wire rod in the air passage of the wire rod is strong at the tip. . This is because the force for advancing the wire has the property of being proportional to the pressure gradient, and the gas such as air and nitrogen is a compressible fluid, so the pressure gradient becomes larger as it gets closer to the tube outlet, that is, closer to the tip of the wire. This is because. It is theoretically known that the force for advancing this wire rod exponentially increases as it approaches the tip of the wire rod, and becomes maximum at the discontinuity of the tip. In FIG. 5, the horizontal axis indicates the distance from the inlet of the pipeline, and the vertical axis indicates the pumping force.

On the other hand, when a similar force is applied to the fragile wire rod which is the object of the present invention, a large traveling force acting on the tip of the wire rod pulls the tip of the wire rod with a large force, and thus the fragile wire rod is urged. May bend tightly to the inner wall at the bend. As a result, the movement of the tip of the wire is stopped, and the wire at the rear part advances, so that it is considered that the wire meanders or bends inside the tube at the rear part of the portion in close contact with the tube. Here, even if the original pressure of the air flow to be used is increased to increase the advancing force, the above-mentioned adhesion is only increased, and the delivery performance is not improved. Further, when the original pressure is lowered, the progressing force becomes small, which is disadvantageous in the transmission.

According to the present invention, since the tip wire having a bending rigidity higher than that of the wire has a high rigidity, it is difficult for the tip wire to come into close contact with the curved portion of the conduit. Therefore, by changing the length to an appropriate value, and replacing the tip of the wire, on which extremely large force is applied, with a tip wire with a large diameter, it is possible to prevent the wire from sticking to the inner wall of the pipeline, and at the same time, with a large original pressure It is possible to send the optical fiber for air feeding.

If the tip wire rod used here becomes long, it means that unnecessary wire rods are sent, resulting in a loss of working time.
Further, since the cost of the tip wire rod is also required, the shorter the length of the tip wire rod, the better.

Further, when the outer diameter of the tip wire is equal to or larger than the outer diameter of the wire, the surface area per unit length of the tip wire is larger than that of the wire. It becomes larger, and a large local force does not act on the tip of the wire. These two effects, that is, the adhesion of the brittle wire at the bent portion of the pipeline is prevented and a large force is not locally applied to the tip of the fragile wire, thereby sending the fragile wire. Is possible.

The optical fiber strands can be assembled from about 1 to about 8 or more, but if the number exceeds 8, the rigidity of the wire increases and the fragile wire targeted by the present invention. There are some cases that do not correspond to the above, and the maximum number is eight. The fragile wire of the present invention is intended for a wire that is difficult to be sent to a pipeline having a bend with a diameter of 1 m or less due to an air flow for the reason described above.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is for explaining one embodiment of the air-carrying optical fiber of the present invention. FIG. 1 (A) is a sectional view of a wire rod, and FIG. 1 (B) is a sectional view of a tip wire rod. It is a figure. In the figure, 1 is a wire rod,
2 is an optical fiber, 3 is a tear string, 4 is a coating, 5 is a tip wire, 6 is a rod member, and 7 is a coating.

The wire rod 1 shown in FIG. 1A has an outer diameter of 250 μm.
The optical fiber 2 of m is used for two fibers, and the tear cord 3 having the same outer diameter is used together with the coating 4 to have an outer diameter of about 0.5 mm. Nylon was used for the coating 4. on the other hand,
In the tip wire rod 5 shown in FIG. 1 (B), the rod member 6 is covered 7
Is applied. In this embodiment, a nylon rod having an outer diameter of 0.9 μm is used as the rod member, and a foamed polyethylene coating 7 is applied to make the outer diameter 1.8 mm. The nylon rod that is the rod member is used to give rigidity to the tip wire rod 5.

The rigidity of the tip member 5 will be specifically described. An example of measuring the bending rigidity will be described with reference to FIG. In the figure, 11 is a horizontal base, 12 is a tip wire, and 13 is a weight. 10c of the tip wire rod 12 from the end of the horizontal table 11 whose surface is horizontal
Then, a weight of 0.5 g was attached to the tip of the tip member 12 to measure the amount of drop H of the tip. Falling amount H is 3
It was appropriate to use a tip member having a bending rigidity of about 9 cm to 9 cm, and the feeding performance was good. The flexural rigidity measured by this method was such that the amount of decrease H was 6.5 cm. When the same measurement was performed on the relatively fragile wire of FIG. 1 (A), the lowered amount H had a rigidity exceeding 9 cm. On the other hand, it was found that when a wire rod having a falling amount H of 3 cm or less was used as the tip wire rod, the wire rod was caught in a curved pipe having a diameter of about 1 m and stopped, so that the wire could not be conveyed.

By changing the length of the tip wire rod 5 in FIG.
Attached to the tip of the tube and used as a conduit to form a bundle with a diameter of 1 m 3
FIG. 4 shows the time required when a polyethylene tube having an inner diameter of 4.5 mm and having a length of 00 m was used and the air pressure was 5 kg / cm ² . When the tip wire is not attached, that is, in the case of 0 cm, when 20 m is fed,
The wire rod did not move and the above-mentioned problems occurred. On the other hand, 1
When the tip wire of cm was attached, the full length of the wire could be sent in 60 minutes, but this is not practical. When the length of the tip wire rod was increased, the time required for sending the entire length could be shortened to 20 minutes when the length of the tip wire rod was set to 5 cm. Further, even if the tip wire is made longer than that, no significant improvement in effect was observed. Therefore, it is practically effective that the tip wire has a length of 5 cm or more.

FIG. 2 is a sectional view of another wire for which the effect of the present invention has been confirmed. In the figure, 1 is a wire rod, 2 is an optical fiber, and 8
Is a central material, and 9 is an aggregate material. FIG. 2A shows an outer diameter of 0.
A 5-mm polyethylene terephthalate core material 8 was interposed, and 8 cores of a UV resin-coated optical fiber 2 having an outer diameter of 250 μm were twisted around the core material 8 to be integrated, and integrated with a assembly material 9 made of UV resin. The outer diameter is 1 mm. Using this wire rod 1, a tip wire rod similar to that of the embodiment described in FIG. 1 was used to conduct a feeding experiment under the same conditions. As a result, 40 m could be fed without the tip wire rod, but a total length of 300 m was fed. It takes 48 minutes when the length of the tip wire is 2 cm.
In order to be able to send the wire within minutes, it was necessary to have a tip wire of 5 cm or more.

The wire rod 1 shown in FIG. 2B has the same outer diameter 2
This is a wire rod having an outer diameter of 0.7 mm, which is obtained by assembling four cores of an optical fiber 2 having a UV resin coating of 50 μm with an assembly material 9 of UV resin. A rod member different from the rod member described in FIG. 1B was attached to the wire rod 1. The rod member is a hollow member excluding the nylon rod at the center in FIG. 1 (B), and is a cylindrical polyethylene foam having an outer diameter of 2 mm. This is used as the tip wire rod, and 5c
When m was attached and a transmission test was conducted using an air flow in the same manner as the above-mentioned experiment, it was possible to transmit 300 m in 21 minutes. Without the tip wire, the transmission stopped at 25 m.
This tubular tip wire rod was lightweight, but the bending rigidity was such that the amount of decrease H in FIG. 3 was 8.5 cm.

The same effect of the tip wire rod has been confirmed even in a ribbon-shaped core wire of 2 to 8 cores in which optical fibers are coated in parallel. As the tip wire rod, a foamed polyethylene jacket with an outer diameter of about 2 mm has the highest effect of improving the permeability, and a minimum outer diameter of 1.5 mm and a maximum of about 3.5 mm is the pressure feeding force received by the tip wire rod. It can be said that it is desirable in terms of frictional force with the pipeline and rigidity.

[0023]

As is apparent from the above description, according to the present invention, a small and fragile wire which is directly coated on a small-diameter optical fiber having a small bending moment and a small bending moment and is bundled is carried by an air flow. It is effective to do.

[Brief description of drawings]

1A and 1B are sectional views of a wire rod, and FIG. 1B is a sectional view of a tip wire rod, for explaining one embodiment of an air-carrying optical fiber of the present invention.

FIG. 2 is a cross-sectional view of another wire for which the effect of the present invention has been confirmed.

FIG. 3 is an explanatory diagram of an example of measuring bending rigidity of a tip member.

FIG. 4 is an explanatory diagram of experimental results.

FIG. 5 is a diagram showing the relationship between the distance from the entrance of the pipeline and the pumping force.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wire material, 2 ... Optical fiber, 3 ... Tear string, 4 ... Coating, 5 ... Tip wire material, 6 ... Rod member, 7 ... Coating, 8 ... Central material, 9 ... Aggregate material.

Front Page Continuation (72) Hideto Machida Inventor Hideto Machida 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A relatively fragile wire rod formed by assembling one or several optical fiber strands and integrating them with a thin resin, and having a bending rigidity with an outer diameter equal to or larger than the outer diameter of the wire rod. An optical fiber core for air delivery, characterized in that a tip wire material having a bending rigidity higher than that of the above is attached. 2. The air-carrying optical fiber according to claim 1, wherein the tip wire has a length of 5 cm or more. 3. A method of gathering one or several optical fiber strands and sending a relatively fragile wire rod integrated with a thin resin to a pipe line by an air flow, comprising: An airflow laying method for an optical fiber, wherein a tip wire rod having an outer diameter that is equal to or larger than the outer diameter of the wire rod and a bending rigidity that is larger than the bending stiffness of the wire rod is attached to the conduit by air flow.